Review of Cabling Techniques and Environmental Effects Applicable

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Review of Cabling Techniques and Environmental Effects Applicable to the Offshore Wind Farm Industry – Technical Report 3.9 Cable Protection for Offshore Wind Farm Developments This section of the report focuses specifically on the various cable protection methods which are relevant to the offshore wind farm industry. This section also includes feedback from cable installation works which have been completed on a number of UK Round 1 offshore wind farms. Cable burial will be the primary cable protection methodology for the export cables which connect the wind farm to the shore and for the inter-array cables which connect the offshore WTGs to each other and inter-arrays. Section 3.9.1 reviews the cable burial methodologies which were presented in Section 3.8 and notes which of these techniques are most relevant for offshore wind farms. The type of cable burial machine which is used on any offshore wind farm project will always be determined by the seabed conditions which exist at the site, the choice of contractor who is selected to undertake the installation work and the availability of appropriate cable burial machines. All of the alternative cable protection methodologies which were described in Section 3.8.6 could potentially be employed on offshore wind farm subsea cables. 3.9.1 CABLE BURIAL OPTIONS FOR OFFSHORE WIND FARMS Within Section 3.8, four separate types of cable burial machine were identified, namely: ● ● ● ● 70 Cable burial ploughs; Tracked cable burial machines; Free swimming ROVs with cable burial capability; and Burial sleds. Table 3.14 provides a summary of each of the above in terms of their relevance and potential application for the burial of offshore wind farm subsea cables. Table 3.15 provides further guidance for each burial device (with the optional configurations of varying burial tools on such devices) on what performance each option is likely to achieve in various seabed sediments. It must be stressed that this qualitative approach is somewhat subjective as within each defined burial device category there will be varying performances linked to the power capability of any given device.
Cable types and installation techniques Table 3.14: Particular Relevance for Cable Burial Machines for Offshore Wind Farms Cable Burial Machine Burial Machine Options Relevance for Offshore Wind Farms Cable Burial Ploughs Cable ploughs are available in varying types: ● Conventional narrow share cable ploughs ● Advanced cable ploughs ● Modular cable ploughs ● Rock ripping ploughs ● Vibrating share ploughs Tracked Cable Burial Machines Free Swimming ROVs with Cable Burial Capability Tracked cable burial machines can be equipped with the following burial tools: ● Jetting systems ● Rock wheel cutters ● Chain excavators ● Dredging systems Free swimming ROVs can be equipped with the following burial tools: ● Jetting systems ● Dredging systems Burial Sleds Burial sleds can be equipped with the following burial tools: ● Jetting systems ● Rock wheel cutters ● Chain excavators ● Dredging systems All types of cable burial ploughs could be employed for the burial of cables on offshore wind farms. The type of plough employed will be determined by the nature of the seabed conditions. It is more likely that the cable ploughs will be used on the export cable routes as the lengths of cable are more suited to the burial method. Tracked cable burial machines could be used for the burial of the export cables, but are more likely to be employed for the burial of the interarray cables for offshore wind farms. The type of tracked cable burial machine will be determined by the nature of the seabed conditions. Those fitted with jetting systems only will be limited to work in sandy and soft clay seabeds whilst those with mechanical cutting tools will have an extended range of use. It is unlikely that free swimming ROVs equipped with a cable burial capability would be widely used for the burial of subsea cables on offshore wind farms. These machines are more commonly used in deeper water applications and when an intervention task such as a repair is required. Burial sleds are typically used for shallow water work and usually require diver assistance for the loading and unloading of cable. They may be utilised for the shore section of wind farm export cables but are unlikely to be used extensively for all cable systems for offshore wind farms as they tend to be less productive and responsive than their tracked cable burial machine counterparts. 71
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REVIEW OF CABLING TECHNIQUES AND EN
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Review of Cabling Techniques and En
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Abbreviations AIS Automatic Identif
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TTS Temporary Threshold Shift TWA T
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3 Cable types and 18 installation t
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6 Good practice measures This secti
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7 Gaps in understanding Research fo
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References Introduction Sinden, G.
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Appendix A: Standards and codes of
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Printed in UK on recycled paper. De
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